Short sleep duration has been shown to be associated with an increased risk for hypertension incidence, but previous prospective studies on this association did not examine the potential effect modifiers of menopausal status, hormone replacement therapy, and shift work or the potential mediator of snoring. Previous cross sectional studies on the relationship between sleep duration and the prevalence of hypertension have shown mixed results. Daytime sleepiness has been shown to be associated with increased risk for stroke and myocardial infarction, but previous studies were not able to control for snoring which is highly emblematic of sleep apnea. Sleep apnea is associated with daytime sleepiness and is an established risk factor for stroke and cardiovascular disease. Previous studies also did not stratify by gender to explore the unique influence of daytime sleepiness in women. The primary goals of this study are to explore the relationship between sleep duration and hypertension in women and to examine potential effect modifiers, mediators, and confounders of this relationship. We will examine the association between sleep duration and the incidence of hypertension using piecewise exponential models and see whether the association varies by age group, menopausal status, receipt of hormone replacement therapy, and engagement in shift work and whether overweight/obesity, type II diabetes, and snoring act as mediators or confounders in the relationship. We will also use logistic regression analyses to examine the cross sectional association between sleep duration and hypertension and use piecewise exponential models to examine the association between changes in sleep duration over the follow-up period and the incidence of hypertension. We also intend to explore the relationship between daytime sleepiness and the incidences of stroke and myocardial infarction and see whether snoring acts as a mediator or confounder of the relationship. The study samples will be drawn from large and well-defined cohorts from the Nurses Health Studies (NHS) consisting of subjects who completed the 1986 and 2000 NHS surveys and the 2001 NHS-II survey that included questions on sleep duration. If short sleep duration increases the risk for the incidence of hypertension then interventions designed to increase the quantity of sleep could act as primary preventative measures against hypertension. Daytime sleepiness could be a prodromal symptom or precursor of vascular events. Increasing severity or pervasiveness of daytime sleepiness could portend vascular events and therefore could be used as an early warning sign to suggest the need for further diagnostic testing or to take precautionary measures. PUBLIC HEALTH RELEVANCE: Blood pressure drops by an average of 10-20% during sleep, so not getting enough sleep raises average 24 hour blood pressure and increases strain on the cardiovascular system that can over time raise the blood pressure equilibrium and lead to hypertension. If short sleep duration increases the risk for hypertension in women then interventions designed to increase the quantity of sleep could help prevent hypertension. Daytime sleepiness could be a prodromal symptom or precursor of vascular events, so increasing severity or pervasiveness of daytime sleepiness could portend vascular events and serve as an early warning sign suggesting the need for further diagnostic testing or to take precautionary measures.